Copyright Goodheart-Willcox Co., Inc. 329 Chapter 16 ∣ Wheels and Tires Spoke angle is the difference in width between the hub and rim spoke attachment points. Figure 16-6 shows spoke angles and the difference between conical and sym- metrical hubs. Because the angles differ from side to side on a conical hub, the holes in the rim must be at the proper angle. Cast Wheels A cast wheel is manufactured by pouring molten metal (usually aluminum or magnesium alloy) into a mold. The hub, spokes, and rim are formed as one piece, Figure 16-7. A cast wheel is very strong and dependable. Some ATVs and UTVs use a billet or other style one-piece wheel. Stamped Wheels A stamped wheel consists of separate parts (hub, spokes, rim) fastened together. Unlike the cast wheel, the stamped wheel is bolted or riveted together. Refer to Figure 16-8. In the case of ATVs and UTVs, the wheel may be two stamped steel or spun aluminum halves welded together in the middle. A stamped wheel has the appearance of a cast wheel, but it is less expensive to manufacture. Hubs and Bearings In most motorcycle wheel designs, wheel bearings are located in the hub. An axle passes through the bearings and connects the wheel assembly to the rear swingarm or front fork legs. Figure 16-9 shows a rear wheel hub. A spacer installed between the bearings allows the axle to be tightened without binding, Figure 16-10. Butted outside spoke Plain inside spoke Throat Head Plain straight spoke Butted straight spoke Length Symmetrical hub Conical hub Goodheart-Willcox Publisher Figure 16-4. Butted spokes are stronger than plain spokes at the head and bend, where spokes usually break. Spoke length is measured from bend or base of head to threaded end. Overall length, spoke size or diameter, length, and angle of throat must be noted for proper wheel assembly. Goodheart-Willcox Publisher Figure 16-5. Both sides of a symmetrical hub are the same diameter, so spokes are all the same length. One side of a conical hub is smaller than the other, so spokes on the small side must be longer. Symmetrical hub Conical hub 10° 10° 12° 16° Hub attachment point Rim attachment point Goodheart-Willcox Publisher Figure 16-6. The spoke angle is the same on each side of a symmetrical hub but different on each side of a conical hub.